The crude gases generated in particular at the start of a coking process in a coke-oven chamber as it is being filled are under considerable pressure since gas can only rise with difficulty through the ever deeper mass of coal. This creates the danger that the high-pressure gases will blow through regions of the door seals exposed to this pressure and thus be released. During the coking process the crude gases generated are less as is the likelihood of an escape. Toward the end of the coking operation there is as a result of the reduced generation of gases in the coke-oven chamber a subatmospheric pressure in the lower region of the coke oven. This creates the danger that outside air can be sucked into the coke-oven chamber and damage the oven.
Coke-oven doors are known in many different embodiments that primarily serve to form a gas-tight closure of the coke-oven chamber. German 2,658,196 (US equivalent U.S. Pat. No. 4,016,045) describes a coke-oven door with a complete peripheral channel formed by elastically compressed seal strips. This gas channel communicates with flues of the coke-oven chamber such that draft is created. If only crude gas flows as a result of insufficient sealing into the gas channel, the gases are sucked by the draft action into the flues. Crude gas can therefore leak from the oven chamber into the atmosphere.
As a result of the connection of the flues with the gas channel the pressure relationships of the flues (draft) are present in the gas channel. A constant subatmospheric pressure is created in the gas channel. This leads to an unwanted sucking of crude gas out of the oven chamber and when the outer seal leaks somewhat there is the danger that air is drawn into the gas channel.